BoilerFaultCodesWhat the manual says
Manufacturer manualConfigure CN1/CN2 main PCB ERROR Temporary communication failure between gas valve and boiler PCB. Replace the main PCB
From this model's manual
Verified against the Baxi/Baxi Bm Baxi B Basic System 2 600 800 Assure 500 Isim installation & service manual, page 48.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register →
Boiler cover options
Avoid the next call-out bill
A cover plan would handle faults like H.01.00: no call-out fees, no surprise bills.
Approved partner
Get a quote →
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Affiliate links. We may earn a commission at no extra cost to you.
All 66 fault codes on the Assure System
Seeing a different code? Every code this model can display, in one place.
101213A.00.28A.00.29A.00.34A.02.06A.02.18A.02.36A.02.37A.02.45A.02.46A.02.48A.02.49A.02.54A.02.55A.02.76E.00 .04E.00 .05E.00 .16E.00 .17E.00 .20E.00 .21E.01 .04E.01 .12E.01 .17E.01 .20E.02 .13E.02 .17E.02 .35E.02 .39E.02 .47E.04 .01E.04 .02E.04 .08E.04 .12E.04 .13E.04 .17E.04 .18E.04 .23E.04 .29E.04 .54E.04 .254E.04.03E.04.10H.00.42H.00.81H.01 .14H.01.05H.01.08H.01.18H.01.21H.02 .00H.02 .02H.02 .03H.02 .04H.02 .05H.02 .09H.02 .10H.02 .70H.02.07H.03 .00H.03 .05H.03 .54H.03.02